enelong@ Laptop?Battery?For Compaq 510 511 610 For Hp Business Notebook 6720S 6730S 6735S 6820S 6830S 500764-001 Hstnn-Lb51 Battery Type : Li-ion Replacement battery Voltage : 10.8V Capacity : 4400mAh; Cell: 6-cell; Color: Black; Built-in circuit protection ensures both safety and stability; Brand New Replacement Product, Works as Genuine Parts; The Replacement Battery come with Full 1 Year warranty;